11. Damaged seeds would on top of water. 12. Cholera is  caused by.

13. Like synthetic fibre , plastic is also a  .

14. Metals react wih acids to produce   gas.

15. The Fire produced by oil cannot be controlled by.

16. Migratory birds fly to far away places because of       changes.

17. cell without well organised nucleus  are called   cells.

18. Time period of a pendulum depends on its .  

19. The size of pupil becomes when you see in dim light.

20. Shrillness of a sound  is determined by the   of vibrationple

please I mark you brainlest ​